1. Field of the Invention
This invention relates to a process cartridge detachably attachable to an electrophotographic image forming apparatus body, and an electrophotographic image forming apparatus to and from which the process cartridge can be attached and detached.
The electrophotographic image forming apparatus referred to above is an apparatus for forming an image on a recording medium by using an electrophotographic image forming system. Such electrophotographic image forming apparatuses include, for example, an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer and a LED printer), facsimile machine, and a word processor.
The process cartridge mentioned above is formed by combining at least one of a charging means, a developing means and a cleaning means as a process means with an electrophotographic photosensitive member in one body into a cartridge. This cartridge is formed so that the cartridge can be attached to and detached from an image forming apparatus body.
2. Description of the Related Art
A process cartridge system has heretofore been employed which is formed by putting together an electrophotographic photosensitive member and a charging means, a developing means and a cleaning means in one body into a cartridge, and fixing this cartridge to an image forming apparatus body so that the cartridge be detachably attachable to the apparatus body. This cartridge system enables the operability of the apparatus to be further improved, and a user to carry out the maintenance of the above-mentioned process means easily. Therefore, this cartridge system is used widely in an image forming apparatus body.
When the process cartridge in such a cartridge system is provided on an outer side of the image forming apparatus body, it is necessary that the electrophotographic photosensitive member (which will hereinafter be referred to as a photosensitive drum) be not exposed to the light. It is also necessary to prevent a user from directly contacting the photosensitive drum to cause an imperfect image to be formed. Therefore, light shielding shutters for covering the photosensitive drum therewith are used. These shutters are made of rigid parts formed out of mainly a resin in many cases.
However, since the shutters are made of rigid members, a space for providing a path along which the shutters are opened and closed, and for storing the shutters is needed.
Under the circumstances, shutters made of a flexible film sheet so as to reduce the space for storing the shutters therein have been devised (refer to, for example, JP-A-2001-282078).
Also, shutters formed by providing a plurality of reinforcement members on flexible sheet members so that the resultant products can be folded like bellows in the longitudinal direction and stored in such a space have been devised (refer to, for example, JP-A-62-278575).
Shutter structures formed out of a flexible material so as to reduce a shutter storage space, and wound up during the use of the shutters to cause a photosensitive drum to be exposed have also been devised (refer to, for example, U.S. Pat. No. 5,231,453).
Shutter structures formed by joining thin, narrow plates together by hinges are drawn into a predetermined storage portion of a process cartridge have also been devised (refer to, for example, U.S. Pat. No. 6,091,916).
The present invention has been attained on the basis of the above-described related techniques by making further improvements thereon.